Ignition system



July 25, 1944. MALLORY 2,354,472

IGNITION SYSTEM Filed May 10, 1943 IN VE TOR.

Patented July 25, 1944 UNITED STATES PATENT OFFICE IGNITION SYSTEMMarion Mallory, Detroit, Mich.

Application May 10, 1943, Serial No. 486,387

5 Claims. (Cl. 200-3l) This invention relates to an ignition system foran internal combustion engine and more particularly to the type ofignition system wherein the spark is advanced and retarded by thepressures'in the intake passageway of the engine.

In the present ignition systems using a centrlfugai governor or intakepressures of the engine to advance the spark, it has been difllcult toproduce different spark advance curves suitable for the different typesof engines, without using a different spring for each advance curverequired. It is one of the objects of this invention to produce a moresimple spark advance mechanism which can be adjusted to effect therequired spark advance curves on many different type engines, with theuse of only one tension spring. This object is achieved by anarrangement for varying the tension of the spring in the spark advancemechanism which co-acts with the pneumatic pressure device forcontrolling the advance of the spark.

In most engines, the spark should start to ad-- vance as soon as thespeed is raised above idle, which is generally 400 R. P. M. However, theslope on which the spark advances in relation to the engine speedgreatly varies in different engines. For example, one engine may require20 spark advance at 3000 R. P. M.; another engine may require 20 sparkadvance at 2500 R, P. M.; while a third engine may require 20 sparkadvance at 2000 R. P. M., but in each case the spark should start toadvance at 400 R. P. M. The spark advances at the same engine R. P. M.on each of the different engines but finishes at a different R. P. M.for each engine. With my invention, the finish of the advance curve cantherefore be varied; i. e., the spark advance mechanism can be adjustedto finish spark advance curve at different engine speeds, withoutchanging the time at which the spark starts to advance. If the mechanismis set so that the spark will start to advance at 400 R. P. M. of theengine, it can be adjusted so that the spark will be fully advanced at3000, 2500, or 2000 R. P. M. and still the spark will start to'advanceat the same point; namely, 400 R. P. M.

Fig. 1 is a plan view partly in section showing my pressure-timedignition system.

Fig. 2 is a section along the line 2-2 of Fig. 1.

My ignition system comprises a stationary housing l, a circuit breakerplate 2 rotatably mounted in housing I, a cam I arranged in the usualmanner to rotate in the direction 01' the arrow, a circuit breaker 4pivotally mounted on plate 2, and an adjustment arm I pivotally mountedto on circuit breaker plate 2 by means of pin I. Arm 5 is adjustableabout pivot 8 by means of an eccentric screw 1 which engages arm 5 inelongated slot 8. Arm 5 is held in adjusted position by means of setscrew 9 which threads into plate 2 and engages arm I on opposite sidesof slot It. A pin ll anchored in arm 5 engages arcuate slot l2 in leverl3 pivoted on pin ll which is anchored in the housing I as at It.Tension spring I6 is connected at one end to pin ll anchored in lever I!and at the other end to pin l8 anchored in the housing I. A suctiondevice comprising a housing 20 is connected by conduit 2la into theintake manifold of the engine (not shown). A flexible diaphragm 2| ismounted in the housing 20 and is biased to the left, Fig. 1, bycompression spring 22. The housing 2i communicates with atmospherethrough opening 23. Diaphragm 2| is connected to circuit breaker plate 2by rod 24. Rod 24 passes through opening 23 in housing 20 and has oneend fixed to the diaphragm 2i and the other end pivotally connected tothe circuit breaker plate 2 by means of pin 25-anchored in plate 2.

The operation of the device is as follows: As the intake manifoldpressures cause suction device 20 to move circuit breaker plate 2 incounter direction to the rotation of cam 3, as indicated by the arrow onplate 2, pin II in arm 5 will start to move in slot l2 of lever ittoward pivot pin l4, thereby giving spring IS a greater leverage overplate 2 and the suction device. Slot i2 is in the form of an arc havingits center at pivot pin 6. If a spark curve is needed which will finishlate or at high engine speed, it will only be necessary to loosen screw9 and turn eccentric screw 1 so that pin II will be closer to pivot pinll: this will give spring l6 still greater leverage over suction device20. If it is desired to have the spark advance finish earlier, arm 5 isadjusted so that pin II will be further away from pin l4 therebydecreasing the leverage of spring 6 over suction device 20.

It is evident from the above that the finish of the spark curve can bevaried without affecting the start of the curve because any adjustmentof arm 5 does not affect the initial tension of spring It. Anyadjustment of arm 5 affects the tension of spring It only after thecircuit breaker plate has started to advance under the influence ofsuction device 20.

It is evident that the above mechanism would be useful in other thanignition systems, for example, it could be used for controlling agovernor throttle valve for an internal combustion engine.

I claim: 1. In combination, a member rotatably supported, a suctionoperated'device connected to said member and adapted to rotate the same,resilient means opposing said suction operated device in the rotation ofsaid member, a stationary anchor, a lever, said resilient means beingconnected to said anchor and lever, a shiltable connection between saidlever and said rotatable member arranged to shift toward the pivot 01said lever as the rotatable member is rotated by said suction devicewhereby the leverage exercised by said resilient means in opposition tothe suction operated device is increased.

2. In combination, a member rotatably supported, a suction operateddevice connected to saidmember and adapted to rotate the same, a tensionspring opposing said suction operated device in the rotation of saidmember, a stationaryanchor, a lever, said tension spring being connectedto said anchor and lever, a shiftable connection between said lever andsaid rotatable member arranged to shift toward the pivot of said leveras the rotatable member is rotated by said suction device whereby theleverage exercised by said tension spring in opposition to the suctionoperated device is increased.

3. In combination, a member rotatably supported, a suction operateddevice connected to said member and adapted to rotate the same through alimited are, a stationary anchor, a lever, a spring between said anchorand lever, a shiftable connection between the lever and rotatable memberarranged to shift relative to the pivot point of said lever as thesuction operated device moves the rotatable member whereby the leverageexercised by said spring in opposition to said suction operated deviceis varied during the rotation of said member.

4. In an ignition system for an internal combustion engine, a housing, acircuit breaker cam rotatable in said housing, a circuit breaker platerotatably mounted in said housing, a suction operated device adapted tobe connected into the intake manifold and connected to said circuitbreaker plate for advancing said plate in counter direction to therotation of the circuit breaker cam as the pressure in the intakemanifold decreases, a lever pivoted on said housing, a pin and slotconnection between said lever and said circuit breaker plate, a springconnected at one end to said lever and at the other end to said housingwhereby the leverage exerted by the spring in opposition to said suctiondevice increases as the circuit breaker plate is advanced by the suctiondevice.

5. In an ignition system for an internal combustion engine, a housing, acircuit breaker cam rotatable in said housing, a circuit breaker platerotatably mounted in said housing, a suction operated device adapted tobe connected into the intake manifold and connected to said circuitbreaker plate for advancing said plate a limited distance in counterdirection to the rotation of the circuit breaker cam as the pressure inthe intake manifold decreases whereby the spark is advanced, a leverpivotally supported on said housing, a spring connected between saidhousing and said lever, an adjustable arm pivoted on said circuitbreaker plate, a. shiftable connection between said arm and leverwhereby, as the circuit breaker plate advances, the said shiftableconnection travels relative to the pivot for said lever and therebyvaries the leverage exerted by said spring in opposition to said suctiondevice, the said adjustable arm being adjustable on said circuit breakerplate and relative to the pivot for said lever to vary the leverageexerted by said spring over said suction device irrespective of theposition of said breaker plate.

MARION MALIDRY.

